Early-onset cardiac arrest, prolonged QT interval, and left ventricular hypertrophy: Phenotypic manifestations of a pathogenic de novo calmodulin variant

Key Teaching Points•Even though CALM variants are not a common cause of long QT syndrome or catecholaminergic ventricular tachycardia, they should nevertheless be considered in the context of a severe or early-onset disease.•The presence of multiple cardiac phenotypes in combination with hypertrophic cardiomyopathy are a novel finding that should be considered.•This case report highlights that the combination of neurologic disorders like attention deficit hyperactivity disorder and dyslexia could be part of the calmodulin phenotype. •Even though CALM variants are not a common cause of long QT syndrome or catecholaminergic ventricular tachycardia, they should nevertheless be considered in the context of a severe or early-onset disease.•The presence of multiple cardiac phenotypes in combination with hypertrophic cardiomyopathy are a novel finding that should be considered.•This case report highlights that the combination of neurologic disorders like attention deficit hyperactivity disorder and dyslexia could be part of the calmodulin phenotype.